1. Field
Exemplary embodiments of the present invention relate to memory units, a memory module, and a memory device.
2. Description of the Related Art
Memory modules are generally adapted for storing data in a data processing system, such as a personal computer (PC), a workstation, a server computer, a communication system and so forth. The data processing system has a plurality of memory chips on a module board therein.
Representative types of memory modules include a Registered Dual In-Line Memory Module (RDIMM) and a Load-Reduced Dual In-Line Memory Module (LRDIMM). These are described below with reference to FIGS. 1 and 2.
FIG. 1 illustrates a typical RDIMM-type memory module 100. FIG. 1 also shows a memory controller 1 in a host which transfers and receives data to and from the memory module 100 and provides the memory module 100 with an address ADDR, a clock CLK, and a command CMD for controlling the memory module 100.
Referring to FIG. 1, the RDIMM-type memory module 100 includes a register 110 and memory units 120_0 to 120_7. The register 110 buffers and transfers the command CMD, the address ADDR, and the clock CLK from the memory controller 1 to the memory units 120_0 to 120_7. Data is directly transferred between the memory controller 1 and the memory units 120_0 to 120_7 without intervention of the register 110.
FIG. 2 illustrates a typical LRDIMM-typed memory module 200. FIG. 2 also shows a memory controller 2 in a host, which transfers and receives data to and from the memory module 200 and provides the memory module 200 with an address ADDR, a clock CLK and a command CMD for controlling the memory module 200.
Referring to FIG. 2, the LRDIMM-typed memory module 200 includes a memory buffer 210 and memory units 220_0 to 220_7. The memory buffer 210 buffers and transfers the command CMD, the address ADDR, and the clock CLK from the memory controller 2 to the memory cells 220_0 to 220_7. Also, the memory buffer 210 buffers and transfers data between the memory controller 2 and the memory units 220_0 to 220_7. In comparison with the register 110 shown in FIG. 1, the memory buffer 210 has the additional function of buffering and transferring data between the memory controller 2 and the memory units 220_0 to 220_7.
With the memory buffer 210 having the additional function of buffering data, the LRDIMM-type memory module 200 may allow/support more logic ranks, achieve a faster response rate, and lower power consumption as compared to the RDIMM-typed memory module 100. The advantages of the LRDIMM-type memory module 200 may be conspicuous when the system has a huge internal memory capacity. However, the LRDIMM-type memory module 200 has the drawback of high manufacturing cost, which is 20% higher than that of the RDIMM-type memory module 100.